The present invention relates to a damper disc suitable for a clutch disc of an automobile or the like.
The clutch disc for the automobile has been improved to prevent noises in driving mechanisms such as a transmission, a differential mechanism and others. Some of the improved clutches have such characteristics that a rate of increasing of a torque increases in stages in accordance with an increasement of a torsion angle, and that hysteresis torque changes dependently on the stages. One of the improvements, which is disclosed in the Japanese Patent Application No. 56-20510 (U.S. patent application Ser. No. 347,157), will be detailed hereinafter with reference to FIG. 1. In FIG. 1, a flange of a splinable hub 1 is divided into a radially inner flange 2 and an outer flange 3. A pair of subplates 4 are fixed to both side surfaces of the flange 3. A torsion spring 5 is disposed between the inner flange 2 and the sub-plates 4. Two kinds of springs 8 (only one is shown) are disposed between the outer flange 3 and a pair of side plates 6 and 7, so that the disc has damping characteristics of three stages. A wave spring 9 functioning as a first friction means is disposed between the flange 2 and each sub-plate 4. Friction washers 10 functioning as second and third friction means are disposed between the sub-plates 4 and the side plates 6 and 7. These friction means cause first, second and third hysteresis torques.
However, in the above clutch disc, since undulations of the wave springs 9 partially contact the flange 2 and the sub-plates 4, long use may cause seizure or the like, and thus, the frictional characteristics may change. Further, the load-compression characteristic of each wave spring 9 is substantially linear as shown in FIG. 2. This causes the following disadvantage. Namely, if a distance between the flange 2 and each sub-plate 4 has an error of .DELTA.l with respect to an intended value of l, a compressed length of each spring 9 also has an error of .DELTA.l with respect to an intended value. This causes a large error of .DELTA.P with respect to an intended compression load. Therefore, the wave springs 9 can not produce a constant hysteresis torque, which may increase noise in a driving mechanism during an idling, a constant running at a high speed and others.
Accordingly, it is an object of the invention to provide an improved disc having a stable first hysteresis torque to reduce the noise in the driving mechanism.
According to the invention, a bushing is disposed between an inner periphery of a sub-plate and an outer periphery of a hub. The bush is provided with an annular flange contacting with a hub flange of the hub. A cone spring is disposed between the radially inner portion of the sub-plate and said flange of bushing. The sub-plate, the cone spring and the bushing are prevented from relative rotation by a stopper means. A friction member is disposed between a radially inner portion of other sub-plate and the flange of the hub.
Other and further objects, features and advanges of the invention will appear more fully from the following description of the preferred embodiments of the invention.